1. Field of the Invention
The present invention relates generally to hydraulic mechanisms. More specifically, the present invention comprises various embodiments of a hydraulic elevator system in which the hydraulic pump and motor are installed at the bottom of the well hole and hydraulic actuator installed therein. The present system includes structure and means to facilitate installation and maintenance of the assembly as well.
2. Description of the Related Art
Elevators generally rely upon one of two principles of operation. Electrically powered traction elevators use cables or wire ropes in their operation, and are installed in relatively taller buildings and structures. Hydraulic elevators use one or more hydraulic cylinder jack and ram assemblies to lift and lower the elevator car. Due to the limitations of strut extension, hydraulic elevators are generally limited to buildings and structures of no more than about six floors in height.
Accordingly, a hydraulic elevator will require a well hole below the elevator hoistway, with the well hole extending downwardly a distance at least slightly greater than the extension length of the hydraulic ram. As a result, most of the hydraulic mechanism is installed in a machine room to one side of the elevator hoistway, or perhaps in a remote location elsewhere in the building, for accessibility during maintenance and repair. This is true for both “dry” systems where the motor and pump are external to the hydraulic tank, and “wet” systems where the motor and pump are installed within the hydraulic tank. Each system has its advantages and disadvantages, but both require a separate machine room, resulting in additional noise, vibration, heat generation into the building, and at least on some occasions, the transmission of various odors into the building.
As a result, a relatively new principle of operation has been developed in Europe and which is now being installed at some locations in the U.S. This is a “machine-roomless” configuration, comprising a traction elevator having the power system installed in the hoistway. However, this system requires a relatively complex hoist cable run, along with two separate sets of guide rails for the elevator car and for the counterweights. System longevity has not been good with such elevators, due to relatively frequent need for cable replacement due to the multiple pulleys and sheaves typically installed in such systems. When cable replacement is required, the job is generally quite cumbersome and time consuming due to the relative complexity of the installation.
Thus, a hydraulic elevator system solving the aforementioned problems is desired.